Ikishoten can reduce the number of hits to 100% TP, but it has to occur in the same cycle as a Conserve TP proc from Emp+2 feet/Ele-belt. Other than that, it's a very slight damage boost from the TP in excess of 100%. Considering that Zanshin has a chance to proc 5% of the time if you're doing things the right way, and Conserve TP procs maybe 10%(?) of the time, the chance of this situation is so small it might as well be ignored.
That being said, I have 5/5 Overwhelm, 4/5 Blade Bash, and 1/5 Shikikoyo. I find having a stun available for those times when it's needed in a pinch invaluable.
As for those recommending holding TP for Hobaku instead of using Blade Bash, HOLY SHIT are you doing it wrong. If you are in that scenario, you are on the wrong job, or at least someone in your group is.
